A SINGLE-STAGE, LIQUID-PHASE DIMETHYL ETHER SYNTHESIS PROCESS FROM SYNGAS III. DUAL CATALYST CRYSTAL GROWTH, DEACTIVATION, AND ACTIVITY CONSERVATION STUDIES

In the liquid phase dimethyl ether (DME) synthesis process, both the methanol synthesis catalyst )composed of CuO, ZnO, and Al₂O₃) and the methanol dehydration catalyst (composed of gamma-alumina) are slurried in the inert oil phase. Various long-term activity checks were conducted on these dual catalysts to characterize the crystal growth and the thermal aging behavior. X-ray powder diffraction, X-ray fluorescence and elemental intensity compositions, and the crystallite size distributions of the aged catalysts were examined. Based on the current investigation, it was established that the crystal growth and the catalyst deactivation problems in the methanol synthesis catalyst are less severe when it is used along with the methanol dehydration catalyst.     

A SINGLE-STAGE,LIQUID-PHASE DIMETHYL ETHER SYNTHESIS PROCESS FROM SYNGAS I. DUAL CATALYTIC ACTIVITY AND PROCESS FEASIBILITY

ABSTRACT

A novel process for manufacturing dimethyl ether (DME) from CO-rich syngas in a single stage has been developed. This novel approach was based on the application of dual catalysis in the liquid phase process, in which two functionally different catalysts are slurried in the inert mineral oil. The experimental reaction rate studies for methanol and dimethyl ether synthesis were conducted in a three-phase, mechanically agitated slurry reactor. The effects of catalyst ratio, temperature, and pressure on the dual catalytic activity were studied. The experimental data bear additional significance because this is the first study of such kind to be conducted on the liquid phase methanol synthesis process.     

A SINGLE-STAGE, LIQUID-PHASE DIMETHYL ETHER SYNTHESIS PROCESS FROM SYNGAS I. DUAL CATALYTIC ACTIVITY AND PROCESS FEASIBILITY

A novel process for manufacturing dimethyl ether (DME) from CO-rich syngas in a single stage has been developed. This novel approach was based on the application of dual catalysis in the liquid phase process, in which two functionally different catalysts are slurried in the inert mineral oil. The experimental reaction rate studies for methanol and dimethyl ether synthesis were conducted in a three-phase, mechanically agitated slurry reactor. The effects of catalyst ratio, temperature, and pressure on the dual catalytic activity were studied. The experimental data bear additional significance because this is the first study of such kind to be conducted on the liquid phase methanol synthesis process.     

A SINGLE-STAGE,LIQUID-PHASE DIMETHYL ETHER SYNTHESIS PROCESS FROM SYNGAS II. COMPARISON OF PER-PASS SYNGAS CONVERSION,REACTOR PRODUCTIVITY AND HYDROGENATION EXTENT

ABSTRACT

In part I of this series on the development of a single-stage, liquid-phase dimethyl ether (DME) synthesis process from syngas, the process feasibility and the process variable effects on the dual catalyst activity were discussed. This part focuses on the comparison of the single-stage reactor productivity of liquid phase methanol synthesis to that of the co-production of methanol and DME. It is experimentally demonstrated that the single-stage reactor productivity for the co-production of methanol and DME could be as much as 60% higher than that for liquid phase methanol synthesis alone. Along with this, a 50% increase in the syngas conversion is also obtained. Further, this approach is shown to co-produce methanol and DME in any fixed proportion, ranging from 5% DME to 95% DME, at significant synthesis rates of DME.     

合成气在以锑改性的HZSM-5分子筛为酸性组份的双功能催化剂上直接转化制二甲醚

 采用固态离子交换法制备了一系列不同氧化锑Sb2O3含量(0~30%)的锑改性HZSM-5分子筛，并以其为酸性组分与铜基甲醇合成活性组分组成双功能催化剂，在连续流动加压固定床反应器上考察了对合成气直接制二甲醚反应的催化性能。结果表明，在温度为260 ℃、压力为4 MPa和原料气空速为1500 ml/(g.h)的反应条件下，HZSM-5分子筛经适量的Sb2O3改性后，产物中二甲醚的选择性由改性前的55%显著提高到69%，而二氧化碳和烃类副产物的选择性则分别由32.4%和9.3%降低到约27%和0.6%。结合NH3-TPD酸性表征结果可知，Sb2O3改性显著提高二甲醚选择性的主要原因是其明显减少了HZSM-5分子筛强酸中心的数量。另外，还考察了反应条件如温度(240-280 ℃)、压力(3-5 MPa)和原料气空速(1500-5000 ml/(g.h))对双功能催化剂反应性能的影响。